This page covers Agniveer Army CEE Work, Energy & Power with complete concept notes, 12 graded practice MCQs, key points and exam-specific tips. Free to study.
Core ConceptRead this first — the foundation of the topic
ENERGY
Energy is the capacity to do work. It exists in many forms but two main types dominate exams: (1) Kinetic Energy - energy due to motion = (1/2)mv², (2) Potential Energy - stored energy = mgh (gravitational). Energy cannot be created or destroyed, only converted from one form to another (Law of Conservation of Energy). Unit is Joule (J)
POWER
Power is the rate of doing work or rate of energy consumption. Power = Work/Time = Energy/Time. Unit is Watt (W). 1 Watt = 1 Joule/second. Commercial unit is kilowatt-hour (kWh). 1 kWh = 3.6 × 10⁶ J.
Formula BlockMemorise — at least one formula appears in every paper
• Work = Force × Distance (W = F × s)
• Kinetic Energy = (1/2)mv²
• Potential Energy = mgh
• Power = Work/Time = Energy/Time
• 1 HP = 746 Watts
Exam PatternsWhat examiners ask — read before attempting PYQs
RRB asks direct formula applications, unit conversions, and energy transformations. Common questions involve calculating work done against gravity, comparing kinetic energies, and power consumption problems.
ShortcutsUse these to save 30–60 seconds per question
ENERGY COMPARISON TRICK
If mass doubles, KE doubles. If velocity doubles, KE becomes 4 times (v² relationship).
2
POWER TRICK
Remember 1 HP = 746 W, 1 kWh = 36 lakh Joules
3
WORK-ZERO TRICK
Circular motion, carrying load horizontally - work done is zero
Worked ExampleSolve this step-by-step before moving on
Exam TrapsCommon mistakes students make — avoid these
#1: Students often confuse work and energy units. Both have same unit (Joule) but power has different unit (Watt). Another major error is forgetting that work done in circular motion or perpendicular direction is zero.
Many students also mix up kinetic energy formula - remember it's (1/2)mv², not mv².
REMEMBER: Energy transformations are everywhere - when you climb stairs, chemical energy converts to kinetic, then to potential energy. Exams love testing these real-life applications with numerical problems.
Key Points to Remember
Work = Force × Distance, measured in Joules (J)
Kinetic Energy = (1/2)mv², depends on velocity squared
Potential Energy = mgh, depends on height above reference point
Power = Work/Time = Energy/Time, measured in Watts (W)
1 Horsepower (HP) = 746 Watts (key conversion for exams)
A man pushes a box with a force of 50 N and moves it 10 m in the direction of the force. How much work is done on the box?
Practice 2easy
Which of the following is the SI unit of power?
Practice 3easy
A ball is thrown vertically upward with a velocity of 20 m/s. At its maximum height, what is its kinetic energy? (Take g = 10 m/s²)
Practice 4easy
A machine does 1000 J of work in 5 seconds. What is the power output of the machine?
Practice 5medium
A force of 20 N is applied on an object to move it 5 meters in the direction of the force. Calculate the work done.
Practice 6medium
An object of mass 2 kg is lifted vertically upward to a height of 10 meters. What is the gravitational potential energy gained? (Take g = 10 m/s²)
Practice 7medium
A vehicle of mass 1000 kg accelerates from rest to a velocity of 20 m/s. What is its kinetic energy at this velocity?
Practice 8medium
A machine does 5000 J of work in 10 seconds. What is the power output of the machine?
Practice 9medium
A ball is dropped from a height of 5 meters. Ignoring air resistance, at what velocity will it hit the ground? (Take g = 10 m/s²)
Practice 10hard
A worker lifts a load of 50 kg vertically upward through a height of 2 meters in 4 seconds. Calculate the power exerted by the worker. (Take g = 10 m/s²)
Practice 11hard
A body of mass 2 kg is moving with a velocity of 10 m/s. If the velocity is reduced to 5 m/s by applying a constant force, what is the change in kinetic energy of the body?
Practice 12hard
A force of 20 N is applied to an object at an angle of 60° to the direction of displacement. If the object moves 5 meters in the direction of force component, calculate the work done.
60-Second Revision — Work, Energy & Power
Remember: Work = F × s, Energy has same unit as work (Joule)
Formula: KE = (1/2)mv², PE = mgh, Power = Work/Time
Conversion: 1 HP = 746 W, 1 kWh = 36 lakh Joules
Trap: Work done in circular motion is zero despite force application
Key: If velocity doubles, KE becomes 4 times (v² relationship)
Pattern: Energy conservation problems are 90% sure to appear
Quick check: Power questions often involve motor efficiency calculations